Art of making vulcanized fiber



P 1941 J. ROBINSON 2,257,576

ART OF MAKING VULCANIZED FIBER Filed April 15, 1940 SHEET 0F PEGENERATED CELLULOSE 0/? ORGAN/C DERIVATIVE 0F ('ELLULOSE Fig. 1

mes 0F lesasusmrsu CELL ULOSE 0/? OAGAN/C DERIVATIVE 0F CELLULOJE A YER OF REGENERA r50 CELLULOSE 0R ORGAN/C ,LAXER 0F WLCANIZED FIBRE D 'R/VAT/VE OFCELLULOSE 4 Fig. 2

LAYERS 0F VULCAN/ZED FIBRE ms or 1256mm r50 csuuzos: 0R ORGAN/C DERIVATIVE orceuuzass rnva 0F mews/10R Lncbusk Fig; 5 LA YA s 0 LAYERS 0F PECFENEPATED VUL CAN/ZED CELL UL 05E 0/? ORGA N/C FIBRE DERIVATIVE 0F CELLULOSE Fig. 3

. INVENTOR. Jay Robinson ATTORNEYA Patented Sept. 30, 1941 2,257,576 r ART or MAKING vnLcAmzEn mm 1 Jay Robinson, Newark, Del., assignor to National Vulcanized Fibre Company, Wilmington, Del.,'- a corporation of Delaware Application April 15, 1940, Serial No. 329,700

15 Claims.

This invention relates to the art of making vulcanized fiber.

Vulcanizedfiber has heretofore been made on a commercial scale by passing one or more webs or sheets of cellulosic material through a gelatinizing bath of suitable concentration and temperature and then combining and consolidating the treated webs or sheets into one multi-ply web I or sheet by means of suitably applied heat and pressure. Among the various gelatinizing agents that have been used or suggested may be mentioned aqueous solutions of alkalis such as caustic soda, diluteacids such as sulphuric, phosphoric, formic and nitric, and salts ;of zinc, tin, anti- -mony and aluminum, and preferably zine chloride. The cellulosic material generally used is an all cotton-cellulose paper, though other cellu' losic materials are mentioned in the chemical literature and are in commercial use.

The gelatinizing agents serve to chemically hydrate, partially hydrolize or gelatinize the cellulose fiber so that when the treated material is laminated and subjected to heat and pressure, it is caused to coalesce and become indissolubly united into a homogeneous multi-ply sheet. At this point, it should be noted that the chemical treatment in the making of vulcanized fiber is much more drastic than the conventional merceriz in'g treatment of cellulosic materials such as cotton for the production of a silk-like lustre. By leaching and puring ou the gelatinizing agent and subsequently drying the sheet, a hard ened horn-like material results having greatly improved characteristics as compared with the cellulose material originally subjected to the chemical and physical treatment. Its toughness,

hardness, elasticity, fiexibiliw or pliability, dielectric strength and the fact that it is oil-proof,

.impervious to organic solvents and fairly resistant to mineral acids render it eminently suitable for many purposes, both mechanical and electrical. Vulcanized fiber as made by prior art methods has, however, one serious drawback or shortcoming which considerably limits its field of usefulness; it is far from being resistant to moisture. Furthermore, even its desirable characteristics are susceptible of a great deal of improvement.

An important object of the present invention is to provide a'vulcanized fiber material having greatly improved and enhanced properties as compared with materials ofthis type produced by prior art methods.

Another object of importance is to provide a vulcanized fiber material having greater resistv ance to moisture than has previously'been considered possible.

A further object is to produce such a'product without using expensive materials or chemica or complicated apparatus or procedures.

Still another object of importance is to greatly enlarge the field of usefulness'of vulcanized fiber materials.

In its very essence, the invention consists in solubly united and bonded together by a chemically hydrated cellulose derived from the cellulose of the layers.

In the following description, the term paper" is to be used in its ordinary significance in the art; namely, as a sheet material formed by papermaking methods or processes from an aqueous suspension containing fibrous material of vegetable origin. The term paper as used in this specification is specifically to exclude regenerated cellulose or cellulose derivatives such as the esters and ethers of cellulose. The term "regenerated cellulose" is to be used to designate a cellulosic material which was first converted into 1 a viscous solution containing a derivative of cellulose and then reconverted into cellulose by coagulation of the solution.

The terms organic derivative of, cellulose," cellulose ester and cellulose ether are to'be given their usual meaning in the field of cellulose.

The term vulcanized fiber" is used in the present disclosure to mean a cellulosic material such as paper, which was first treated with a gelatinizing or parchmentizing agent and then subjected to heat and pressure to impart thereto a hardness and density not ordinarily possessed by the untreated material.

Referring. now briefly to the drawing:

Figure 1 is a view in perspective of a portion of a sheet or web of regenerated cellulose or organic cellulose derivative or mixture of these materials, that may be used in practicing the present invention;

Figure 2 is a similar view of a laminated product consisting of one layer of the material of Figure '1 and one layer of vulcanized fiber;

Figure 3 is a similar view 01' a. laminated product consisting of layers ofthe material of Figure l and layers of vulcanized fiber, the two sets of layers being arranged in alternating relation-.

ship Figure 4 is a similar view of a laminated prodnot, the facing layers being made from the material of Figure 1 and the other layers being made from vulcanized fiber; and

Figure 5 is a similar view of the product of Figure 4 after a coating of varnish or lacquer has been applied to the outer surfaces thereof.

The raw materials of the presentinvention consist of one or more sheets or webs of paper and one or more sheets or Webs of regenerated cellulose or of an organic derivative of cellulose such as cellulose ester or ether, or of a mixture of two or more of such materials. As previously stated, regenerated cellulose designates a cellulosic material'which was first converted into a viscous solution containing a cellulose derivative and then reconverted into cellulose by coagulation of the solution. My invention is not restricted to any particular method of producing,

the regenerated cellulose; the nitrocellulose process, the viscose process and the cuprammonium process are all suitable for my purpose.

As has been stated, the organic derivative of cellulose may be an ether or an ester of cellulose. As examples of suitable ethers may be mentioned ethyl cellulose, propyl cellulose, and benzyl cellulose. As examples of suitable esters of cellulose may be mentioned the esters of fatty acids such as cellulose acetate, cellulose propionate, cellulose butyrate, cellulose stearate, cellulose laurate and cellulose palmitate. The esters of aromatic acids such as cellulose benzoate as well as certain of the mixed esters are also suitable. Among the suitable mixed esters may be mentioned cellulose 'aceto-propionate, cellulose aceto-butyrate and' Similar mixed esters of the higher fatty acids. Mixed cellulose ethers as well as the cellulose ether-esters are also suitable. The cellulose ether-esters may be prepared by the physical admixture of a cellulose ether with a cellulose ester, by the esterification of cellulose ethers, or by the etherification of cellulose esters.

The regenerated cellulose, cellulose ester or cellulose ether may be in the form of woven or knitted fabrics of spun fibers as artificial silk, or it may be in the form of sheets or webs such as the material obtainable on the market under the trade-marks Cellophane, Sylphrap, Transparit, Plastacelle, Kodapak, Ethofoil," and Tenite. The sheets may each be made entirely of regenerated cellulose; cellulose ester or cellulose ether or a mixture of two or more of these materials. lulose, cellulose ester or cellulose ether may be in the form of a coating or film on one or both sides of a sheet or web of paper or other fabric. The coating may be applied in various ways. For instance, in the case of regenerated cellulose a suggested method consists in passing the sheet or web to be coated through a solution of vficose and then through a cellulose-regenerating solu-, tion to deposit the coating or film of regenerated cellulose. In the case of a cellulose ester or ether, the coating may be applied to the sheet or web in the form of a solution by dipping, brushing, roll coating or spraying.

The layers that are to be formed into the laminated product of the invention are. subjected to the action of a gelatinizing agent, such as zinc chloride or sulphuric acid, as in the prior art methods of making vulcanized fiber. For a description of several suitable prior methods, reference is hereby made to Shoemaker Patent No.

As a variation, the regenerated cel- L these materials.

1,675,667 issued July 3, 1928, to The National Vulcanized Fibre Company, the assignee of the present invention, and to an article by F. L. Simons in the May and June 1930 issues of Cellulose entitled Vulcanized fibre." The gelatinized layers are then superposed and combined by means of heat and pressure, leached of gelatinizing agent and finally dried also in the manner previously practiced in the art of making vulcanized fiber.

In Figure l, I have shown a single layer or thickness of regenerated cellulose, cellulose ester or cellulose ether, or a mixture of two or more of these materials, that may be used in making the laminated product of the invention.

In Figure 2 is illustrated a slab of material consisting of two layers of thicknesses, one layer being made from vulcanized fiber and the other from regenerated cellulose, cellulose ester or cellulose ether, or a mixture of two or more of these materials. This product may be made by passing 1 a web of paper and a web of materialcomposed of regenerated cellulose, cellulose ester or cellulose ether or of a mixture of two or more of to enable it to be combined with the gelatinized layer of regenerated cellulose, cellulose ester or cellulose ether.

The product of Figure 3 consists of a number 0! layers or thicknesses, certain of the layers being made from vulcanized fiber and the others being made from regenerated cellulose, cellulose ester, cellulose ether or a mixture of two or more of The layers are arranged in alternating relationships.

In Figure 4 is illustrated a slab of material, the body portion of which is made from vulcanized fiber and the facing layers of which are made from regenerated cellulose, cellulose ester, cellulose ether or a mixture of two or more of these materials. The layers may be united in the manner previously mentioned.

In Figure 5 is shown the product of Figure 4 after its surface layers have been given a coating of varnish or lacquer. Any suitable varnish or lacquer may be employed. Among the many varnishes or lacquers that may be used may be mentioned coating materials containing synthetic resins and/or cellulose esters which are available on the market.

By incorporating in a vulcanized fiber product one or more sheets or layers made of regenerated cellulose, cellulose ester, cellulose ether or of a mixture of two or more of these materials, I have found it possible greatly to enhance the desirable characteristics of vulcanized fiber as well as to reduce to a minimum its shortcomings. Not only does the product of, this invention have greater dielectric strength than had previously been considered possible, but its bursting strength, tensile strength and tearing strength have been greatly increased. The product resists bending stresses to a remarkable degree and willnot crack or break even when severely bent. Furthermore, it has a greatly increased moisture resistance and its surface finish is greatly improved. At a result of its improved surface finish, only one coating of varnish or lacquer is necessaryto completely cover its surface. The completeness with which one coating closes the surface pores is evidenced by the fact that a tacky material such as unvulcanized rubber can be readily stripped ofl'.

The foregoing description embodies the essential and distinctive thought which characterizes my invention. It is to be understood, however, that the disclosure is intended to be illustrative rather than restrictive, and that no limitations are to be imported which are not required by the language of the appended claims or the state of the prior art.

The present application is a continuation in part of application Serial No. 68,671 filed March 13, 1936.

I claim:

1. As an article of manufacture, a laminated product consisting of one or more layers of vulcanized fiber and one or more layers of a cellulosic material selected from thegroup consisting of regenerated cellulose, an organic ester of cellulose and a cellulose ether, all the layers being bonded together by a chemically hydrated cellulose derived from the bonded layers.

2. As an article ofmanufacture, a laminated product consisting of one or more layers of vulcanized fiber and one or more layers of regenerated cellulose, all the layers being bonded together by a chemically hydrated cellulose derived from the bonded layers.

3. As an article of manufacture, a laminated product consisting of one or more layers of vulcanized fiber and one or more layers of viscose, all the layers being bonded together by a chemically hydrated cellulose derived from the bonded layers.

4. As an article of manufacture, a laminated product consisting of one or more layers of vulcanized fiber and one or more layers of cellulose acetate, all the layers being bonded together by a chemically hydrated cellulose derived from the bonded layers.

5. As an article of manufacture, a laminated product consisting of one or more layers of vulcanized fiber and one or more layers of a cellulose ether, all the layers being bonded together by a chemically hydrated cellulose derived from the bonded layers.

6. As an article of manufacture, a laminated product comprising a body portion of vulcanized fiber and a facing layer of a cellulosic material selected from the group consisting of regenerated cellulose, an organic ester of cellulose and a cellulose ether, said facing layer and said body portion being bonded together by a chemically hydrated cellulose derived from the bonded layers.

7. As an articl of manufacture, a laminated product comprising a body portion of vulcanized fiber and a facing layer of regenerated cellulose bonded to said body portion by a chemically hydrated cellulose derived from the regenerated cellulose.

. 8. As an article of manufacture, a laminated product comprising a body portion of vulcanized fiber and a facing layer of viscose bonded to said body portion by a chemically hydrated cellulose derived from the viscose.

.9. As an article of manufacture, a laminated product comprising a body portion of vulcanized fiber and a facing layer of cellulose acetate bonded to said body portion by a chemically hydrated cellulose derived from the cellulose acetate.

10. As an article of manufacture, a laminated product comprising a body portion of vulcanized fiber and a facing layer of a cellulose ether bonded to said body portion by a chemically hydratedcellulose derived from the cellulose ether.

11. As an article of manufacture, a laminated product consisting of a number of layers of vulcanized fiber and a number of layers of a material selected from the group consisting of regeneratecl cellulose, an organic ester of cellulose and a cellulose ether, said layers being arranged in alternating relationship and being bonded together by a chemically hydrated cellulose derived from the bonded layers.

12. As an article of manufacture, a laminated product consisting of a number of layers of vulcanized fiber and a number of layers of regenerated cellulose, said-layers being arranged in alternating relationship and being bonded together by a chemically hydrated cellulose derived from the bonded layers.

' 13. As an articl of manufacture, a laminated product consisting of a number of layers of vulcanized fiber and a number of layers of viscose, said layers being arranged in alternating relationship and being bonded together by a chemically hydrated cellulose derived from the viscose.

14. As an article of manufacture, a laminated product consisting of a number of layers of vulcanized fiber and a number of layers of cellulose acetate, said layers being arranged in altemating relationship and being bonded together by a. chemically hydrated cellulose derived from the cellulose acetate.

15. As an article of manufacture, a laminated product consisting of a number of layers of vulcanized fiber and a number of layers of a cellulose ether, said layers being arranged in alternating relationship and being bonded together by a chemically hydrated cellulose derived from the cellulose ether.

JAY ROBINSON. 

